1. Field of the Invention
The present invention relates to a reaction apparatus for atomic layer deposition (ALD). More particularly, the present invention relates to a reaction apparatus for ALD that is able to maintain the pressure and the flow of a reactant gas in a reaction chamber.
2. Description of the Related Art
Atomic layer deposition (ALD) technology, wherein reaction mixtures are sequentially input and removed, is one of several possible thin-layer growing technologies necessary in the fabrication of semiconductor devices. A reaction apparatus for ALD deposits atomic layers on a surface of a specimen using reactant gases that react with the surface of the specimen.
FIG. 1A illustrates a schematic view of a conventional reaction apparatus for ALD using a traveling method. Here, the traveling method, i.e., a continuous gas flow method, continuously supplies gases to a specimen in order to deposit atomic layers. Referring to FIG. 1A, gases are continuously supplied through a gas inlet 11, which is connected to a reaction chamber 13, wherein input gases react with a specimen 17 arranged in the reaction chamber 13 to form atomic layers on the surface of the specimen 17. Thereafter, the gases are exhausted to the outside through a gas outlet 15.
The conventional reaction apparatus for ALD using the traveling method reduces the amount of time required to switch gases and forms atomic layers having excellent uniformity; however, it is difficult to apply to a large-sized substrate.
FIG. 1B illustrates a schematic view of a conventional reaction apparatus for ALD using a showerhead method. Here, in the showerhead method, reactant gases are sprayed onto a specimen via a showerhead arranged in a reaction chamber. Referring to FIG. 1B, gases are input to a reaction chamber 23 via a gas inlet 21 and evenly sprayed onto a specimen 27 through a showerhead 29. Thereafter, the gases are exhausted to the outside through a gas outlet 25.
The conventional reaction apparatus for ALD using the showerhead method easily forms atomic layers on a large-sized substrate; however, it is difficult to adjust a distance between the specimen 27 and the showerhead 29.
The reaction apparatuses for ALD of FIGS. 1A and 1B have gas outlets 15 and 25 having a size larger than a size of the corresponding gas inlets 11 and 21, respectively. Accordingly, whereas residual reactant gases after the reaction process can be easily exhausted to the outside, the apparatuses require a large amount of reactant gases because these structures require the reactant gases to be continuously supplied during the reaction process. In addition, the conventional reaction apparatus for ALD is fabricated in a single unit so that it is difficult to additionally install an analyzer that measures reaction by-products generated during the reaction process or that measures the thickness, the density, or the chemical binding state of the atomic layers.